Outer Part for Homokinetic Joints and Rolling Bearings

ABSTRACT

The invention is developed on the basis of an external part for homokinetic joints and rolling bearings, wherein the external part (1) has an annular sealing surface (12) on at least one of its end faces, Axially extending drillholes (15) are created on the end face in the external part (1) to accommodate fastening means, wherein the sealing surface (12) extends radially between the drillholes (15) and the inner diameter of the external part (1) in the region of the drillholes (15).According to the invention, a contour (16) which protrudes from the sealing surface (12) is arranged on the one or more end face sealing surfaces (12) of the external part (1), against which contour a gasket (13) is pressed in the assembled state. This protruding contour (16), with a longitudinal section in the form of a lug, offers a small pressing surface for the gasket (13) even in the pre-assembled state so that its position is secured without use of an adhesive even with small pressing forces such as are normally applied when the component to which the external part (1) belongs is pre-assembled, as well as during transport of the component and subsequent work steps.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is the U.S. national stage of International ApplicationNo. PCT/DE2019/100846, filed on 2019 Sep. 25. The internationalapplication claims the priority of DE 102018124078.3 filed on 2018 Sep.28; all applications are incorporated by reference herein in theirentirety.

BACKGROUND

The invention is developed on the basis of an external part forhomokinetic joints and rolling bearings according to the preamble ofclaim 1.

Joints and bearings are typically sealed on the end face by means offlat gaskets, which are pressed against the end face of the externalpart by a cover element which seals off the joint or bearing. For thispurpose, drillholes are created in the ring-shaped end face of theexternal part, in which the fastening means such as screws, pins, rivetscan be inserted or through which the screws, pins or rivets can passthrough the external part. Since the sealing surfaces are “planar faces”and the drillholes in the gasket have a radial play with respect to thefastening means, there is a risk that the gasket will shift duringtransport of a component which has only been pre-assembled, and whoseelements have not yet been attached to each other with the pressingforce prescribed for operation, or during downstream work steps thereonor final assembly of the component itself. In order to prevent thegasket from shifting or lifting away from the sealing surface, which isalready relatively narrow in the radial direction, it is known toinitially stick the gaskets to the planar surface with adhesive tosecure them for transport. For example, a power transmission systemdesigned in the form of a universal constant velocity joint is knownwhich has an outer ring connected to a second shaft via a screwconnection, an inner ring connected to a first shaft via a splinedelement, and a cage which accommodates ball bearings. On the end faceopposite the second shaft, the joint is terminated with a closing plate,and on the end face opposite the first shaft it is terminated with aboot via an adapter. Each end face of the outer ring is furnished withan annular depression into which a gasket is placed and then centred bythe depression. The gaskets are glued to the respective end face of theouter ring 2 (US 2003/0 042 690). The dis-advantage of gluing consist inthat it represents an additional work step, which furthermore entails acertain time to allow the adhesive to dry or cure. Only specialadhesives with fast-acting bonding properties which also do not attackthe gasket material can be considered for use as the adhesive.Accordingly, it may happen that different adhesives have to kept on handfor different gasket materials. The extra work step and the adhesiveincrease the costs of the joint and the rolling bearing.

An external part 3 of a constant velocity joint with a sealing surfacefor an annular gasket is also known. This gasket has a sealing profilewhich is formed by a radially outer, first sealing element and aradially inner, second sealing element. The two sealing elements in theform of O-rings are connected to each other by a connecting bridge and aform-stabilising element. A circumferential hollow is present on bothsides of the connecting bridge. In order to secure the radial positionof the gasket, the contact surface of the external part or of the coverwhich seals the external part is furnished with a limiting fin (DE 102009 018 373 A1).

Finally, a constant velocity joint with integral internal joint part isalso known, consisting of an external joint part with inner bearingraces, an internal joint part with outer bearing races assigned to theinner bearing races, and ball bearings accommodated in a ball bearingcage. The external joint part can be connected to a connecting elementand sealed on the side facing said connecting element with a closingcover. The internal joint part is embodied as an integral internal jointpart which is connected to a shaft part so as to be non-destructivelydetachable therefrom and is sealed on this side by means of a flexiblesealing element facing towards the external joint part (DE 10 2016 007495 A1).

In view of the above, it is the object of the invention to reduce thelabour and cost associated with securing a gasket on the pre-assembledjoint or rolling bearings, and thereby ultimately to guarantee thesealing function of the gasket when the joint or rolling bearings are inthe operating state.

SUMMARY

The invention is developed on the basis of an external part forhomokinetic joints and rolling bearings, wherein the external part (1)has an annular sealing surface (12) on at least one of its end faces,Axially extending drillholes (15) are created on the end face in theexternal part (1) to accommodate fastening means, wherein the sealingsurface (12) extends radially between the drillholes (15) and the innerdiameter of the external part (1) in the region of the drillholes (15).

According to the invention, a contour (16) which protrudes from thesealing surface (12) is arranged on the one or more end face sealingsurfaces (12) of the external part (1), against which contour a gasket(13) is pressed in the assembled state. This protruding contour (16),with a longitudinal section in the form of a lug, offers a smallpressing surface for the gasket (13) even in the pre-assembled state sothat its position is secured without use of an adhesive even with smallpressing forces such as are normally applied when the component to whichthe external part (1) belongs is pre-assembled, as well as duringtransport of the component and subsequent work steps.

DETAILED DESCRIPTION

The advantage of the external part according to the invention with thecharacterizing features of claim 1 over the related art describedearlier is that it guarantees that once set during pre-assembly theposition of the gasket required to ensure reliable sealing function ofthe gasket in the operating state is maintained even under the loadsexerted on the gasket during transport and subsequent work steps withoutany additional work steps or securing means. This securing means iseffected solely with the pressing forces that are normally brought tobear on the gasket during pre-assembly.

These advantages are realised according to the invention in that acontour which typically protrudes vertically from the sealing surface inthe axial direction is arranged on each of the end faces which functionas sealing surfaces, against which contour the gasket is already pressedin the assembled state while the external part is in the pre-assembledstate. Even in the pre-assembled state, this contour, whose longitudinalsection protrudes in the manner of a lug, offers a small pressingsurface for the gasket so that its position is secured without use of anadhesive even with small pressing forces such as are normally appliedwhen the component to which the external part belongs is pre-assembled,as well as during transport of the component and subsequent work steps.

The dimensions of the protruding contour, particularly its height,depend on the nature of the gasket, in particular its thickness and thematerial it is made from.

The contour can be arranged in any regions on the sealing surface, thatis to say in the region of either the outer or the inner diameter of thesealing surface or in the region between the inner and outer diametersof the sealing surface. The most effective sealing surface possible inthe pre-assembled state is created when it is arranged in the region ofthe outer diameter.

According to an advantageous variant of the invention, the protrudingcontour extends without interruption around the circumference, i.e. itforms a closed ring. With regard to manufacturing, this can be createdsimply, for example by turning, and can also be applied practically forouter rings of rolling bearings. In order to affix the gasket securely,however, it is entirely sufficient to dispose the protruding contouronly in the form of segments on preferred regions of the sealing surfaceof the external part.

This is also advantageous from a manufacturing point of view forexternal parts of homokinetic swivel joints, for example. With externalparts of this kind, a particular feature compared with their use inrolling bearings consists in that the external joint part includes innerball races which extend axially or at an angle to the swivel axis of thejoint for the ball bearings inside the joint that transmit the turningmoment from the internal part thereof to the external joint point, or inthe opposite direction. The bridges that remain between each of the twoinner ball races extend axially as far as the sealing surface of theexternal joint part, wherein the coaxial inner surface of the bridges isdesigned as a guide surface for a ball cage to accommodated the ballbearings. The drillholes for fastening the closure cover together withthe gasket are arranged on the end face in the region of the bridges andcoaxially with the swivel axis of the joint. As a consequence, thesealing surface on the end face extends between the drillholes and isguided radially inwardly in the region of the drillholes, in other wordshere it extends over the end face surface of the bridges. With anexternal joint part of such kind, in view of this not perfectly annulargeometry of the sealing surface it is appropriate from a manufacturingpoint of view to construct the contour which protrudes vertically fromthe sealing surface in the axial direction not continuously but insteadto arrange the sealing surface either between the drillholes or in theregion of the bridges between the drillholes and the inner circumferenceof the sealing surface.

According to another advantageous variant of the invention, when viewedin cross section the protruding contour has at least one shell surfacewhich extends conically with respect to the axis of the external part.

According to another advantageous variant of the invention, when theprotruding contour is viewed in cross section the transition of at leastone of its shell surfaces has the form of a radius towards the sealingsurface.

According to an equally advantageous variant of the invention, theprotruding contour has a flat bearing surface for the gasket. Thisserves to prevent the contour from cutting into a gasket which is madefrom a relatively soft material.

Further advantages and advantageous variants of the invention may bediscerned from the following description, claims and drawing.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the object according to the invention arerepresented in the drawing which illustrates an example of an externalpart for a homokinetic joint and which will be explained in greaterdetail below. In the drawing:

FIG. 1 shows a longitudinal section of a constant velocity jointconnected to a shaft journal,

FIG. 2 shows a detail X in the sealing region of the external part ofthe constant velocity joint with gasket in the pre-assembled state,

FIG. 3 shows a detail X in the sealing region of the external part ofthe constant velocity joint with gasket in the finally assembled state

FIG. 4 shows a first variant of the gasket retainer according to theinvention,

FIG. 5 shows a second variant of the gasket retainer according to theinvention,

FIG. 6 shows a third variant of the gasket retainer according to theinvention and

FIG. 7 shows a fourth variant of the gasket retainer according to theinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

As may be seen in FIG. 1, the constant velocity joint has an externaljoint part 1 with inner ball races 2 and an internal joint part 3 withouter ball races 4, may be positioned coaxially, displaced and swiveledby means of ball bearings 5 which are arranged between the inner andouter ball races 2 and 4 in the external joint part 1. The ball bearings5 are accommodated and retained in a cage 6 whose outer circumferencebears on the inner circumference of the external joint part 1. ThisInner circumference is formed by the inner surfaces of the bridges 7which remain between the inner ball races 2 and will be referred to inthe text below as the cage guide surface 8. A shaft journal 9 isinserted in the internal joint part 3 and is sealed against the externaljoint part 1 by means of a flexible cuff 10 and a cap 11. On the endface opposite this sealing arrangement, the external joint part 1 has anend face sealing surface 12, via which the constant velocity joint issealed with a gasket 13 and a cover 14. Cover 14 and gasket 13 arescrewed to the housing internal part, and the housing part is furnishedwith drillholes 15 in the region of the bridges 7 for this purpose.

FIGS. 2 and 3 illustrate the bearing of the gasket 13 on the sealingsurface 12 of the external joint part 1 as detail X from FIG. 1, whereinFIG. 1 shows a component consisting of external joint part 1, gasket 13,cover 14 and connecting elements—not shown here—in the pre-assembledstate, that is to say with a gasket 13 pressed lightly against theexternal joint part 1 by means of the connecting elements. This figureclearly shows the contour 16 protruding in accordance with the inventiona few tenths of a millimetre axially from the sealing surface 12, whichcontour secures the gasket 13 against the external joint part 1 evenunder light pressure so that it is held in position even while thecomponent is being transported, during downstream joining operations andwhen it is subsequently installed in a motor vehicle, without damagingthe gasket 13. In this pre-assembled state, the gasket 13 lies flush inline with the axially protruding contour 16. FIG. 3 shows the samecomponent in the finally assembled state, wherein the gasket 13 is nowpressed fully against the sealing surface 12 of the external joint part1, and the axially protruding contour 16 passes into the gasket 13, andthe gasket 13 is pressed against the sealing surface 12 of the bridge 7.

FIGS. 4 to 7 show two different arrangements and three different crosssectional shapes of the radially protruding contour 16. In the variantsrepresented in FIGS. 4 to 6, the radially protruding contour 16 isarranged in the region of the inner diameter of bridges 7 on which thecage guide surface 8 is supported. FIG. 7 shows the arrangement thereofin the middle of the sealing surface 12 of bridges 7. Thecross-sectional shape of the contour 16 may be rectangular, trapezoidalon one or both sides. If the cross-sectional shape is rectangular, abroad, flat bearing surface 17 is created (FIG. 5), in which case it isadvantageous to provide the one or more shell surface(s) f protrudingvertically from the sealing surface 12 with a transition radius 18. Ifthe cross-sectional shape is trapezoidal (FIGS. 4, 6 and 7), theprotruding contour 16 tapers conically into a transition with thesealing surface 12, so the bearing surface of the gasket 13 is smaller.

The detail drawings in FIGS. 2 to 7 show another special feature of thedesign of the cage guide surfaces 8 which is independent of the resentinvention: The cage guide surfaces 8 have an alignment which is guidedradially in the direction of the swivel axis of the external joint part1 towards the sealing surface 12. Consequently, the radial thickness ofthe bridges 7 increases or, expressed in a different way, the bridges 7have a radial overhang 19 which has the effect of radially enlarging thewidth of the sealing surface 12 on the bridges 7 in the region of thedrillholes 15.

All of the features represented here may be essential to the inventioneither individually or on any combination with each other.

LIST OF REFERENCE NUMERALS

-   1 External joint part-   2 Inner ball race-   3 Internal joint part-   4 Outer ball race-   5 Ball bearing-   6 Cage-   7 Bridge-   8 Cage guide surface-   9 Shaft journal-   10 Cuff-   11 Cap-   12 Sealing surface-   13 Gasket-   14 Cover-   15 Drillhole-   16 Axially protruding contour-   17 Flat bearing surface-   18 Transition radius-   19 Radial overhang

1. External part for homokinetic joints and rolling bearings, whereinthe external part (1) has an annular sealing surface (12) on at leastone of its end faces, and axially extending drillholes (15) are createdon the end face in the external part (1) to accommodate fastening means,wherein the sealing surface (12) extends radially between the drillholes(15) and the inner diameter of the external part (1) in the region ofthe drillholes (15), characterized in that a contour (16) whichprotrudes from the sealing surface (12) is arranged on the one or moreend face sealing surfaces (12) of the external part (1), against whichcontour a gasket (13) is pressed in the assembled state.
 2. Externalpart according to claim 1, characterized in that the protruding contour(16) extends circumferential without interruption.
 3. External partaccording to claim 1, characterized in that the protruding contour (16)is arranged in the region of the outer diameter of the sealing surface(12).
 4. External part according to claim 1, characterized in that theprotruding contour (16) is arranged in the region of the inner diameterof the sealing surface (12).
 5. External part according to claim 1,characterized in that the protruding contour (16) is arranged in theregion between the inner and outer diameters of the sealing surface(12).
 6. External part according to claim 1, characterized in that whenviewed in cross section the protruding contour (16) has at least oneshell surface extending conically towards the axis of the external part(1).
 7. External part according to claim 1, characterized in that whenthe protruding contour (16) is viewed in cross section, the transitionof at least one of its shell surfaces to the sealing surface (12) isconstructed as a radius (18).
 8. External part according to claim 1,characterized in that the protruding contour (16) has a flat bearingsurface for the gasket (13).